1. Field of the Invention
The present invention relates to a gaseous-diffusion electrode usable for reduction-oxidation of gases and cold fusion, and applicable to fuel cells, secondary cells, electrolytic apparatus, electrochemical synthesis apparatus, etc. and an electrochemical reactor using the gaseous-diffusion electrode.
2. Description of the Related Art
In fuel cells, secondary cells and the like, gaseous-diffusion electrodes have heretofore been usually composed of a gaseous-diffusion layer, a reaction layer and a current-collecting plate.
When used in an electrolytic apparatus, the gaseous-diffusion electrode is composed so that an electrolysis solution and a supplied gas may come into contact with the reaction layer side and the gaseous-diffusion layer side, respectively, of the electrode. In the electrolytic apparatus, the electrolysis solution permeates into the reaction layer, which is hydrophilic, and reaches a catalyst metal supported on the reaction layer. On the other hand, the supplied gas reaches the catalyst metal on the reaction layer via the gaseous-diffusion layer, which is hydrophobic, and an electrochemical reaction is carried out on the reaction layer.
Such a gaseous-diffusion electrode have heretofore been generally known and has been disclosed, for example, in Japanese Patent Application Kokai (Laid-Open) No. 62-154585.
A gaseous-diffusion electrode is required to have a function of receiving a gas from the surface of the gaseous-diffusion layer of the electrode, conducting the gas to the reaction layer of the electrode to subject the same to electrochemical reaction, and discharging the gas produced by the reaction from the gaseous-diffusion layer of the electrode. For this function, it is preferable to keep a large portion of the surface of the gaseous-diffusion layer always in contact with the gas to be received.
In such an electrolytic apparatus as is described above, the gaseous-diffusion layer is in direct contact with the electrolysis solution and hence is attacked by the electrolysis solution, resulting in an insufficient durability of the electrode.
An object of the present invention is to solve the above problems and provide a gaseous-diffusion electrode which exhibits sufficient gaseous reduction-oxidation ability and an excellent durability even when partly immersed in an electrolysis solution.
Another object of the present invention is to provide an electrolytic apparatus most suitable for using the above gaseous-diffusion electrode therein.